"(Customers) say things they shouldn't have. It just wasn't nice," says Curtis West, who worked 19 Black Fridays over the course of his 24 years as an employee at Macy's. West doesn't work there anymore, but when he first started at the Macy's flagship store in New York City, Black Friday sales started at 5 a.m. the day after Thanksgiving. Now, the store plans to open at midnight.

The post-Thanksgiving tradition is now starting sooner than ever -- almost competing with late holiday feasting on Thanksgiving day. Toys R Us, Sears, Wal-Mart and Target are all opening their doors between 8 p.m. and 9 p.m. on Thursday evening.

Store employees have to show up even earlier to prepare for the retail rush. Others have to lose sleep as they work long, hectic overnight shifts at stores that remain open all hours of the night.

Macy's spokesman Jim Sluzewski said that Macy's waits until after Thanksgiving to open so associates can spend the day with family. He said that the store asks for volunteers to staff the overnight shift and it gets a good response.

But according to West, working on Black Friday wasn't much of a choice. That's because Macy's only pays workers for time off on Thanksgiving if they work both the day before and the day after the holiday, he said.

For West, the pressure came from both ends.

At home, his family was upset with him for spending less time during the holiday with them.

At work, the mile-long lines of shoppers, the opening of Santa Land and the mad dash for limited quantities of deeply discounted items soon devolved into a nightmare for employees.

"It's a very stressful atmosphere for workers," he said. "Everyone's in a rush. They want the sale and then they want to get out of there and get to Kmart."

"Doorbusters" make things more hectic. Customers get frustrated after waiting hours for deals that sell out even before they get in the store. And workers usually bear the brunt of customers' anger.

"When the store runs out of merchandise the day of advertising, no one understands why you don't have it," West said. "Normally, it's hard to get a manager to deal with the issue."

Black Friday traditionally marks the start of the holiday shopping season each year. Stores consider it the most important time of the year, because they can make up to 40 percent of their annual sales in the November-December period.

West isn't the only store employee upset about working Black Friday. Last week, more than 20 new petitions were created on Change.org calling on retailers to push back their opening times so that workers can spend Thanksgiving at home.

One of the petitions, started by Target employee Casey St. Clair, has nearly 170,000 supporters on the advocacy website. St. Clair is asking Target to "take the high road and save Thanksgiving for employees."

A Target spokesperson said the store's opening time was carefully evaluated. "Thanksgiving weekend is one of the busiest of the year, and we appreciate our Target team's flexibility on this weekend and throughout the holiday season," she said.

Wal-Mart workers have also started a campaign to fight against the store's 8 p.m. open time. OUR Walmart, an organization of Wal-mart workers, has been speaking out against the retailer's holiday hours.

In the 22 hours after the group shared a photo of an angry cat on its Facebook page with the caption, "'Like' if you think Thanksgiving should stay a day for family not working and shopping," the photo got over 1,100 likes, 240 "shares" and 100 comments.